Mg clt clutch relay location to fix ac

[GrimaceRunner]

First off thank you to everyone for all the info on here. Learning way more about A/C than I ever thought I would... This thread seems so close to what I'm dealing with, I hope it's ok to piggy back here. 2000 Manual Transmission SR5. Manual AC controls.

My AC stopped working when I replaced the AC switch on the dash (old one kind of broke & popped off) with a genuine Toyota replacement (Genuine Toyota 84660-35030 A/C Switch). Just a plug n play swap.

When I did that, the AC stopped working altogether. Switch light would turn on, but the AC wouldn't work. Took it to my go-to shop, and was quoted a ton of money to replace items they thought were the culprit (AC Amp, Evaporator Core & Expansion Valve). I had them replace the AC Amplifier (OEM 88650-35060) as it was lowest man hours involved, but it didn't solve the issue.

At this point, I dove into the forums and decided to go after all these parts myself rather than pay a shop $$$$, following BamaDrewski's writeup here: DIY Complete AC Replacement on 2000 T4R Limited

I replaced:
-Compressor
-Evaporator Core
-Expansion Valve
-Receiver/Dryer Unit
-All O rings & the H and L valves on the AC lines
-AC Pressure Switch

All items are Denso or OEM, save for the O ring kit and Santech AC switch per what BamaDrewski used

Brought it to a shop to do the vacuum test & refill. Passed the vacuum test, but the compressor would not turn on after the machine loaded the system with freon. Needless to say I didn't get to take my air-conditioned victory lap home. The shop and I agreed I'm dealing with something electrical at this point, so I left with the system filled with freon so I can troubleshoot on my own & have the system ready to go once I find the culprit.

My question for the folks on this thread, is what should I be checking next, given that the AC Amplifier has been replaced? Could my problem possibly be tied to this new AC switch I bought? I'm not too savvy with how to test electrical systems but could figure it out if there's a good writeup out there.

Side note, my AC Amplifier was located inside the housing described by Syndragy, so there's some 00's out there with that config as well!

Thanks for humoring me & for any help you can provide!

 

[brillo_76]

First off thank you to everyone for all the info on here. Learning way more about A/C than I ever thought I would... This thread seems so close to what I'm dealing with, I hope it's ok to piggy back here. 2000 Manual Transmission SR5. Manual AC controls.



My AC stopped working when I replaced the AC switch on the dash (old one kind of broke & popped off) with a genuine Toyota replacement (Genuine Toyota 84660-35030 A/C Switch). Just a plug n play swap.



When I did that, the AC stopped working altogether. Switch light would turn on, but the AC wouldn't work. Took it to my go-to shop, and was quoted a ton of money to replace items they thought were the culprit (AC Amp, Evaporator Core & Expansion Valve). I had them replace the AC Amplifier (OEM 88650-35060) as it was lowest man hours involved, but it didn't solve the issue.



At this point, I dove into the forums and decided to go after all these parts myself rather than pay a shop $$$$, following BamaDrewski's writeup here: DIY Complete AC Replacement on 2000 T4R Limited



I replaced:

-Compressor

-Evaporator Core

-Expansion Valve

-Receiver/Dryer Unit

-All O rings & the H and L valves on the AC lines

-AC Pressure Switch



All items are Denso or OEM, save for the O ring kit and Santech AC switch per what BamaDrewski used



Brought it to a shop to do the vacuum test & refill. Passed the vacuum test, but the compressor would not turn on after the machine loaded the system with freon. Needless to say I didn't get to take my air-conditioned victory lap home. The shop and I agreed I'm dealing with something electrical at this point, so I left with the system filled with freon so I can troubleshoot on my own & have the system ready to go once I find the culprit.



My question for the folks on this thread, is what should I be checking next, given that the AC Amplifier has been replaced? Could my problem possibly be tied to this new AC switch I bought? I'm not too savvy with how to test electrical systems but could figure it out if there's a good writeup out there.



Side note, my AC Amplifier was located inside the housing described by Syndragy, so there's some 00's out there with that config as well!



Thanks for humoring me & for any help you can provide!

I actually had a magnetic clutch clip, but I didn't snap in. So the wire slowly vibrated loose.

I would verify that the connection is good.

If good disconnect that connector on the compressor and using a wire with clips carefully apply battery voltage to the compressor connector and the mag clutch should engage. If not. You have a ground or magnetic clutch issue.


Sent from my SM-A536V using Tapatalk

 

[GrimaceRunner]

I actually had a magnetic clutch clip, but I didn't snap in. So the wire slowly vibrated loose.

I would verify that the connection is good.

If good disconnect that connector on the compressor and using a wire with clips carefully apply battery voltage to the compressor connector and the mag clutch should engage. If not. You have a ground or magnetic clutch issue.


Sent from my SM-A536V using Tapatalk

Thanks Brillo, I'll try that when I have some time & report back. The new Denso compressor was a full assembly, so it came with new mag clutch and connections. So hopefully it works a-ok as that took a hot minute to install

Does verifying continuity help confirm/deny any of this? I checked continuity for the magnetic clutch, per the manual you linked earlier in this thread and got "good tone" from my multimeter: https://www.pnw4runners.com/pdf/AC_HEATE.PDF

Also curious if something like the thermistor that connects w/ the evaporator core, or the pressure switches may be the culprit, as those would automatically stop the compressor from working, correct?

Thanks for the help!

 

[brillo_76]

Thanks Brillo, I'll try that when I have some time & report back. The new Denso compressor was a full assembly, so it came with new mag clutch and connections. So hopefully it works a-ok as that took a hot minute to install



Does verifying continuity help confirm/deny any of this? I checked continuity for the magnetic clutch, per the manual you linked earlier in this thread and got "good tone" from my multimeter: https://www.pnw4runners.com/pdf/AC_HEATE.PDF



Also curious if something like the thermistor that connects w/ the evaporator core, or the pressure switches may be the culprit, as those would automatically stop the compressor from working, correct?



Thanks for the help!

The switches in the ac will cut the mag clutch . They are safety switches to protect the compressor.

So verify it's plugged in good. It should have continuity as it's a magnetic clutch. [ which is a coil] Very low resistance only a few ohms].


The power to the magnetic switch itself will verify that's all good.

I am suspecting a safety switch or electrical issue on this one.

Sent from my SM-A536V using Tapatalk

 

[GrimaceRunner]

The switches in the ac will cut the mag clutch . They are safety switches to protect the compressor.

So verify it's plugged in good. It should have continuity as it's a magnetic clutch. [ which is a coil] Very low resistance only a few ohms].


The power to the magnetic switch itself will verify that's all good.

I am suspecting a safety switch or electrical issue on this one.

Sent from my SM-A536V using Tapatalk

I think I'm getting closer to a resolution...

Connection is good on the compressor. I have continuity to the compressor coil (when read from the AC Amp wire connector), but no voltage going to it (when read from the compressor connector), which leads me to believe the AC Amp is blocking said voltage because of a safety mechanism...

Checked the pressure switch, now that the system has freon in it, and I get continuity. So that works and I know the system is in the "green" in terms of pressure.

Checked the Evaporator temp sensor (thermistor)... FSM says to check the harness just above the AC amplifier, which should give back a standard reading of 1,500 Ohms at 77 degrees. My multimeter was giving me just under 1,200 Ohms at 79 degrees. FSM states clearly to replace if it isn't right around 1,500 Ohms, but gives no tolerance range...

Anyone familiar with what kind of range is tolerable for that thermistor? 1,200 seems low, but I am not an electrical guru so I'm not sure if that's enough of a disparity from the preferred 1,500 Ohms to shut the whole system down, ie not send power to the compressor.

Pretty sure the thermistor is the culprit...
Any thoughts? Am I making sense??